Electric discharge apparatus



March 9, 1943. L. R. PETIERS 2,313,575

ELECTRIC DI SCHARGE APPARATUS Filed Jan. 27, 1941 L Inventor:

Leo R. Peter's,

His Attorney.

Patented Mar. 9, 1943 UNITED, PATENT OFFICE Leo R. Peters, EastCleveland, Ohio, assignor t General ElectricGompany, a' corporationofNew York Application January 27, Iii ll, Serial No. 376,087, 7 Claims.(01. 176 -124) My invention relates to electric, discharge apparatus ofthe type comprising a, gaseous electric discharge device provided withthermionic; electrodes and arranged to be operated from a,

sourceof alternating currentv supply. It'relates, particularly toapparatus such as disclq fid. by Figfl of the Wels Patent 1,951,112.

Apparatus such as disclosed by that figure has been found to have theobjection that the time required for the heat responsive switch toreclose after an interruption in the current supply is indeterminate andin eneral too long for. present purposes. It is the object of myinvention to provide improved. apparatus of that type which will avoidthe above noted objection and will maintain the switch at temperatureshaving a limited range of variation.

My invention will be better understood from the following descriptiontaken in connection with the accompanying. drawing, and its scope willbe pointed out, in the appended claims.

Referring tothe drawing, Fig. 1 is a circuit diagram illustrating oneembodiment of my invention, Fig. 2 is a top view of a commercial form ofthe switching mechanism andFig. 3 is'a side view thereof.

In the drawing, i represents a gaseous electric discharge device such asa discharge lamp having the thermionic electrodes 2 and 3 thereinillustrated as filaments which are'arranged to be initially heated to anelectron emitting temperature before the startingvoltage is applied tothe device. The lamp is shown connected to be operated from a suitablesource of alternating current supply 4 which may be a Gil-cycle, 115'-volt lighting circuit. The connections between the lamp and the source 4are represented by 5 andfi, each of which connects with an electrode atone end thereof. shown including the main switch I and'the bal: last 8for. the lamp which is represented as 'a reactor,

Forcompleting a circuit by which heating current may flow throughthe'lamp electrodes to effect the initial heating thereof, I'have 'pro5vided. the thermal or heat responsive switch). The movable contact oftheswitch is actuated by the bimetallic strip H, one end of which isfixed and is connected with the otherend of the electrode 2. Thecooperatingfixed front contact I2'is shown supported on the bimetallicstrip l3 which is connected with the other end'ofthe electrode 3 and isnormally engaged by the con-. tactcarried by the strip II when thelatteris not heated. The strip H is heated by, the resistance heater Mwhich is arranged in thermal relation therewith and which is connectedin series in the connection 5. The switch II) also is provided with theback contact l5 which is normally spaced only a small distance from themovable These connections are.

contact when the same is in engagement with the contact l2 and which isshown supported oii the. bimetallic strip it. The switch parts are shownenclosed in the evacuated envelope 9, which, if desired, may contain asmall amount of; an, inert gas. The contact I5 is connected through theresistor H with that end of the heater l4 which is remote from thedevice I. Very satisfactory operation with this apparatus has beenobtained when the resistance of the resistor 57 has been approximatelyequal to that of the heater i4. With this contruction the heating of thebimetallic strip II by its heater will cause it to bend away from thecontact l2 into engagement with the contact l5, whereupon heater and theresistor in parallel. The sever-a1 bimetallic strips are arranged tobend in the same direction with an increase in the temperature of theambient whereby compensation is made for such temperature changes.

When the apparatus is initially connected with the source of supply 4 byth closing of the switch 1; a discharge does not immediately start inthe device as the voltage applied thereto is insufiicient. Current flowsin series, however, through the switch, the reactor, the heater, theelectrode 2, the thermal switch including parts H, l2 and I3, and theelectrode 3, the electrodes being quicklybrought to an electron emittingtemperature. since the current at this time is approximately twiee thatwhich flows through the device during its, normal operation. The heatingof the bi- 'metallic strip I l causes it to warp away from the contactl2, thereby opening the circuit between the electrodes and causing astarting voltage'to be; applied tothe lamp in the well understoodmanner. The discharge having started in the device, heat is stillsupplied by the heater to the bimetallic strip II, and although of lessdegree;

than before, still it is sufiicient to hold the strip away from thecontact l2. Were there no back contact IS, the strip would finally cometo rest at, a position which is somewhat indefinite, de pending uponvarious factors. By employingthe back contact l5 spaced only a shortdistance away and connected through the resistor ll with the heater M,the engagement of the contact This reduction in the,-

repeated. Thus it will be seen that the heating of the bimetallic stripl l is never materially more than that required to move it through thesmall space separating it from the back contact. This has the importantadvantage that in the event of an interruption of the source of currentsupply the time required for the reclosing of the switch can bedetermined with considerable exactness and also is reduced to apracticable minimum. Were the back contact L to be connected directlywith the end of the heater without the resistor, the resistance changein the connection between the device and the source would be that due tothe full effect of the heater as the switch alternately connects anddisconnects with its back contact. However, by using a resistor such asshown at I! in the connection with the back contact, the change inresistance with the operation of the switch is reduced and where theresistance of the resistor is approximately equal to that of the heater,the change in resistance is only about half of what it would be withoutthe use of the resistor.

A further advantage is that, whereas a certain amount of flicker oftenoccurred at that end of the lamp having the electrode 2 due to thetendency of the discharge to jump from one end of that electrode to theother at each make and break of the switch with the back contact, theuse of the resistor ll avoids such flicker.

A commercial form of the above described switch in which the bimetallicsupporting strips 13 and 46 are not used is represented in Figs. 2 and 3where the parts are shown mounted in an evacuated sealed receptacle H!which also contains the resistor 17. If desired, the receptacle maycontain a small amount of gas, for example, 1 to 2 cm. of nitrogen, inorder to provide for a greater rate of heat transmission to thebimetallic strip from the heater and a greater rate of heat loss fromthe strip. Figs. 2 and 3 show the envelope comprising the metal baseplate l9 and the metal cap 20 sealed thereto. To the several terminalstuds 21 which are sealed in the base plate are secured the bimetallicstrip II, the two switch contacts 12 and i5, which in this case arefixed, the heater and the resistor, as will clearly appear. Thebimetallic strip ii is shown in the form of a spiral of one turnsurrounding the heater which is a spiral or coil of resistance wire.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In electric discharge apparatus comprisingan electric dischargedevice connected to be operated from a source of alternating currentsupply and provided with thermionic electrodes, a resistance heater insaid connection, a heat responsive time delay switch in thermal relationtherewith and connected between said electrodes to control the flow ofheating current therethrough, and means comprising a member arranged tocooperate with said switch and operative during the operation of saiddevice to reduce the heating of said switch in response to a determinedopening movement thereof.

2. In electric discharge apparatus comprising an electric dischargedevice connected to be operated from a source of alternating currentsupply and provided with thermionic electrodes, a resistance heater insaid connection, a heat responsive time delay switch in thermal relationtherewith and connected between said electrodes to control the flow ofheating current therethrough, and means comprising a contact member inthe path of movement of said switch operative after the device hasstarted and responsive to a predetermined opening movement of saidswitch for reducing the heat supplied by said heater.

3. In electric discharge apparatus comprising an electric dischargedevice connected to be operated from a source of alternating currentsupply and provided with thermionic electrodes, a resistance heater insaid connection, a heat responsive time delay switch in thermal relationtherewith and connected between said electrodes to control the flow ofheating current therethrough, and means comprising an additional contactfor said switch operative after the device has started and responsive toa predetermined small opening movement of said switch for reducing theheat supplied to the switch.

4. In electric discharge apparatus comprising an electric dischargedevice connected to be operated from a source of alternating currentsup- .ply and provided with thermionic electrodes, a resistance heaterin said connection, a switch connected between said electrodes tocontrol the flow of heating current therethrough comprising a thermallyresponsive element adjacent to said heater and a circuit controlled bythe movement of said element for supplying discharge current to thedevice in shunt with said heater.

5. In electric discharge apparatus comprising an electric dischargedevice connected to be operated from a source of alternating currentsupply and provided with thermionic electrodes, a resistance heater insaid connection, a bimetallic switch in thermal relation with saidheater and connected between said electrodes to control the flow ofheating current therethrough, a circuit for supplying discharge currentto said device in shunt with said heater, and means actuated by theopening movement of said switch for closing said circuit.

6. In electric discharge apparatus comprising an electric dischargedevice connected to be operated from a source of alternatin currentsupply and provided with thermionic electrodes, a resistance heater insaid connection, a switch comprising a front contact and a cooperatingbimetallic member in thermal relation with said heater connected betweensaid electrodes to control the flow of heating current therethrough,said switch having a back contact and a resistance connected betweensaid back contact and that end of said heater the more remote from saiddevice.

'7. An electric discharge lamp having thermi onic electrodes, a leadarranged to connect one end of each of said electrodes with a source ofalternating current supply, a resistance heater in one of said leads, aswitch comprising a bimetallic strip in thermal relation with saidheater and connected with the other end of one of said electrodes, saidswitch having a front contact connected with the other end of the otherof said electrodes and having a rear contact and a resistor whoseresistance is approximately equal to that of said heater connectedbetween said rear contact and said heater at the end thereof remote fromsaid lamp,

LEO R. PETERS.

, CERTIFICATE OF CORRECTION. Patent, No. 2,513,575. March 9, 1915.

LEO R. PETERS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 65, for "determined" read --predetermined; and thatthe said Letters Patent shofild be read with this correction thereinthat the same may conform to the record of the case in the PatehtOffice.

Signed and sealed this 20th day of April, A. D. 1915.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

CERTIFICATE OF QORRECTION. Patent No. 2,515,575. March 9, 1&5.

LEO R. PETERS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 65, for "determined' read predetermined-; and thatthe said Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 20th day of April, A. D. 1915.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

